1.5 GB would be too large to send through email, but Technical Support has other methods to receive the file. Once you contact Technical Support, a representative will send you a link where you can upload the zipped archive.

The next day I got an email from Thomson Reuter in Bangalore India. I followed their request and sent an 1.3Gb zipped archive of the Literatur.Data folder there, Now I wait, if they find out, what's wrong, why the rebuild with Endnote doesn't work.